The present invention generally relates to a flow control valve and more particularly, relates to a flow control valve that contains no moving parts other than an inflatable bag positioned in a cavity of the valve.
In a manufacturing facility, various chemicals in gaseous and liquid form are used in various fabrication processes. For instance, in a semiconductor fabrication plant, a semi-conducting substrate must be processed in a multiplicity of manufacturing steps, i.e., as many as several hundred in order to complete an integrated circuit chip. The multiplicity of manufacturing steps may include cleaning, cooling, deposition, etching and any other necessary processing steps. A variety of chemicals, including liquids and gases must be used in these steps. For instance, to clean or cool a process chamber or a wafer platform, to etch a specific feature on a substrate, to clean after each etching or deposition steps, to deposit layers of materials on a substrate, or to carry out any other processes.
The variety of chemicals used in a semiconductor facility must be handled with care since some of the processing chemicals are highly toxic and/or highly corrosive. For instance, strong acids are frequently used in an etcher for the etching of metals for forming a conductive path. Since hazardous materials are not always all consumed in chemical processes, unused hazardous chemicals must be recycled or otherwise disposed of. Due to their hazardous nature, the materials must be carefully handled during their storage and transportation to avoid personal injuries and potential fire hazard. The mechanical components used in transporting these materials should therefore be minimized such that potential exposure of personnel to the chemicals may be reduced.
Since a large number of chemicals utilized in a semiconductor fabrication facility are of the flammable or toxic nature, i.e., other than those inert gases normally utilized as purge or carrier gases, the storage and transporting of such chemicals are important aspects in the management of a fabrication facility. For instance, to avoid fire, explosion and serious personal injuries, a flammable or toxic gas must be securely stored in a safe storage facility. The storage of these gases is usually kept away from the plant personnel and thus, away from the processing equipment where they will be used. The transporting or delivery of these gases to a processing equipment therefore becomes another important aspect in the management of a fabrication plant.
A typical gas delivery system utilized in a semiconductor fabrication facility is shown in FIG. 1. The system 10 includes a main process gas input line 12 and a main purge gas supply line 14. A process gas, after being fed into the main process gas input line 12, is transported through a two-way air actuated valve 16 into a main process gas supply line 18. Off the main process gas supply line 18, a number of two-way, diaphragm-type (hereinafter, diaphragm) control valves 20 are utilized to feed the process gas from the main supply line 18 into a three-way diaphragm control valve 24. Into the three-way diaphragm control valve 24, a purge gas is also fed from the main purge gas supply line 26 into a second gas inlet 23 of the three-way diaphragm control valve 24. The purge gas, i.e., an inert gas, fed through the inlet 28 is then mixed with the process gas fed through the inlet 22 and outputted from outlet 32 of the three-way diaphragm control valve 24. It should be noted that in the above example, the purge gas is utilized as a carrier gas for the process gas. The purge gas may also be used alone for purging the gas line without the process gas. In such application, the three-way diaphragm control valve is adjusted such that only inlet 28 is connected to outlet 32 of the valve, while inlet 22 is shut-off.
When the purge gas is used as a carrier gas, the gas mixture is sent through a gas pressure regulator 36, a pressure transducer 38 into a second three-way diaphragm control valve 42 through inlet 40. The process gas/carrier gas mixture then exits from either outlet 46 or 48 and is fed into a process equipment. It should be noted that in FIG. 1, the process equipment and the gas lines feeding to the process equipment are not shown for simplicity reasons. When the gas outlets 46, 48 are not connected to a process equipment or to a gas delivery line, the outlets 46, 48 are capped by a cap 50. In the gas distribution system 10 shown in FIG. 1, the main process gas input line 18 is further provided with an expansion valve 60. The expansion valve 60 is provided such that other gas output lines may be connected thereto allowing future expansion of processing equipment in the fab facility. The outlets 62, 64 are also capped by caps 66 when the expansion valve 60 is not in use for add-on additional gas supply lines.
In the gas distribution system 10, it is seen that a number of two-way or three-way diaphragm-type control valves, i.e., 20, 24 and 42 are utilized for controlling the flow of various gases, including those of the flammable or toxic nature or vacuum in the supply lines. The control valves are equipped with control handles mounted on top of the valves such that a handle may be turned either clockwise or counterclockwise to close or open the gas passage.
FIG. 1A illustrates a cross-sectional view of an automated diaphragm valve 26 without the manually operated handle. It is seen that the diaphragm valve 26 is constructed with several moving parts, for instance, a spring 30, a control diaphragm 34, a spindle 44 and a sealing diaphragm 52. Any of the moving parts 30,34,44 and 52 may fail during the operation of the valve 26 and therefore cause serious problems for the fluid supply system 10. It is therefore desirable to provide a flow control valve for controlling fluid used in semiconductor fabrication that is essentially without any moving parts and therefore is more reliable in operation.
It is therefore an object of the present invention to provide a flow control valve that does not have the drawbacks or shortcomings of the conventional flow control valves.
It is another object of the present invention to provide a flow control valve that utilizes a minimum number of moving parts inside the valve.
It is a further object of the present invention to provide a flow control valve that can be advantageously used in semiconductor fabrication processes.
It is another further object of the present invention to provide a flow control valve that does not utilize any moving parts.
It is still another object of the present invention to provide a flow control valve for use in semiconductor manufacturing by utilizing an inflatable bag in a cavity of the valve.
It is yet another object of the present invention to provide a flow control valve by enclosing in a cavity formed by two end plates in a cylindrical-shaped housing and providing apertures in the end plates and an inflatable bag in the cavity.
It is still another further object of the present invention to provide a flow control valve that incorporates an inflatable bag wherein the bag does not substantially block a fluid flow passageway in the cavity of the valve when deflated but blocks the fluid flow passageway completely when inflated.
It is yet another further object of the present invention to provide a flow control valve incorporating an inflatable bag wherein the bag may be inflated by N2, air, water or oil.
In accordance with the present invention, a flow control valve for use in a fluid flow supply system that does not contain moving parts in relation to the valve housing is disclosed.
In a preferred embodiment, a flow control valve is provided which includes a valve housing that has a cylindrical-shaped wall, a first and a second end plate sealingly engaging an inner periphery of and positioned spaced-apart in the valve housing, each of the two end plates has at least one aperture therethrough; a valve cavity formed in-between the two end plates and an inner periphery of the valve housing defining a fluid passageway therein; and an inflatable bag positioned inside the valve cavity in fluid communication with a fluid inlet tube such that when a fluid is flown through the fluid inlet tube into the inflatable bag, the bag inflates to partially block or completely block the fluid passageway in the valve cavity.
In the flow control valve, the inflatable bag may be fabricated of a corrosion-resistant elastomer, or fabricated of an elastomer that comprises fluorosilicone. The valve housing may be fabricated of a corrosion-resistant material or stainless steel. The first and the second plate may have a plurality of apertures therethrough each has a diameter less than 1 cm. The valve housing may further include an inlet and an outlet each adapted for connecting to a fluid conduit, or an inlet and an outlet each equipped with a quick-connect-disconnect fitting. The fluid inlet tube penetrates through one of the two end plates for inflating the inflatable bag, or the fluid inlet tube penetrates through one of the two end plates and the cylindrical-shaped wall of the valve housing for feeding a fluid into the inflatable bag. The cylindrical-shaped wall of the valve housing may have a diameter between about 1 cm and about 10 cm. The inflatable bag may be inflated by a fluid selected from the group consisting of N2, air, water and oil. The inflatable bag may be inflated by N2 to a pressure inside the inflatable bag between about 0.5 Kg/cm2 and about 25 Kg/cm2. The at least one aperture may have a diameter between about 0.1 cm and about 1 cm. The cylindrical-shaped wall of the valve housing may have a diameter of at least 2 cm and the first and second end plates being positioned spaced-apart by at least 2 cm.
The present invention is further directed to a flow control valve which incorporates an inflatable bag therein that is constructed by a tubular-shaped valve housing that has an inlet end and an outlet end; two end plates positioned perpendicular to and space-apart in the valve housing defining a cavity therein-between, each of the end plates may be provided with a plurality of apertures; and an inflatable bag positioned inside the cavity, the bag does not substantially block a fluid flow path in the cavity when deflated, but blocks the fluid flow path completely when inflated by a flu-d medium flown into the bag through an inlet tube.
In the flow control valve incorporating an inflatable bag therein, the plurality of apertures may each have a diameter between about 0.1 cm and about 1 cm. The tubular-shaped valve housing and the two end plates may be fabricated of a corrosion-resistant material. The inflatable bag may be fabricated of a corrosion-resistant elastomer. The fluid medium used in inflating the inflatable bag may be selected from the group consisting of N2, air, water and oil.